New engine need help

[predator5100]

Hey i got my new well rebuilt 3.4 back with bored out cylnders .02 over and heads worked i want so badly to smash the gas and have yet to do so whats a good way to break it in i've put 268 miles on it so far i want to feel the gas for two reasons to make sure they did a good job and it will run good whats the rule for breaking in engines

[GregWS6'01]

you dont' wanna over do it.....wait till a little after 500 miles or so. Give your seals time to seat before u go nailing on it. You need to run it good up till that time though. Don't take it on short runs.....
you'll also see over time as u put more mileage on it that you'll get more horsepower over time as it breaks in. blah

[predator5100]

i have had a few probs with it already such as backfire and hesistation (that might be caused by my cat it went bad last week) And my temp guage reads 245 before the fan kicks on i have changed the coolant sensor twice) How much can i expect if i've bored the block and ported the heads

[GregWS6'01]

I can't help ya there..sorry bud

[HAZ-Matt]

<blockquote>quote:</font><hr>Originally posted by GregWS6'01:
You need to run it good up till that time though. Don't take it on short runs.....<hr></blockquote>

You need to worry mostly about operating at the same rpm for extended periods of time. During a break in period, you need to run it throughout the rpm band, while avoiding full throttle starts.

[predator5100]

so if i ease the peddle down it should be o.k

[GregWS6'01]

yea, I left out that RPM bit. DOn't redline it, but let your car see anywhere from idle up to 4000rpm's. Just go easy on it. If i were you, I'd also go and change the oil around 500 miles, and change it to synthetic.....

[HAZ-Matt]

<blockquote>quote:</font><hr>Originally posted by GregWS6'01:
If i were you, I'd also go and change the oil around 500 miles, and change it to synthetic.....<hr></blockquote>

I'm no expert, but if it's anything like a new engine you are not supposed to change the oil early. They'll even tell you that at an oil change place.

[3.4 slow to go]

don't go to synthetic untill break in period is over.